The problem with stables isn't the stables themselves, but rather the usefulness of pets. If Taming were improved, then stables would be able to hold their ground as investments.
The buffs currently offered at stables is very lacking. I think that the range of buffs available from pets needs to be broadened and made more useful. Reload, regen, lifesteal, skill buffs (for non taming related skills), and so much more could easily be implemented into the buffs available at the stables.
Pets should become more useful ingame.
Certain pets should be able to extract mining resources for you, and carry them back to you (perhaps only certain humanoid pets and requiring the use of an extractor so as not to devalue the extractors themselves, and still induce appropriate decay for the utility of the feature).
All pets should replace the role of decoys, with a special ability (like a trick) to go pull aggro from a mob that is attacking you, and distract it long enough for you to get away.
To facilitate this a pet could have an HP bar, and when the pet's HP is depleted by the aggressor mob, then the pet "dies" and respawns in your inventory with 0 HP, which can naturally regen (like us) or be healed with a healing tool.
- This would provide a useful purpose for pets having skills/HP.
These are just a few ideas, there are so many potential uses for pets.... Fix pets and implement the new buffs into the stables and it solves both problems.